There are numerous publications in the patent literature which describe dispersants, which are either phosphate esters of polyester chains containing a terminating hydroxy group, or which are polyester amines obtained by reacting a polyester chain having a terminating carboxylic acid group with a polyamine or polyimine, such as polyethyleneimine. For example, WO 94/21368 discloses a dispersant comprising a polyethyleneimine residue carrying polyester chains derived from a caprolactone and at least one other specified lactone or hydroxycarboxylic acid; WO 99/55763 discloses a similar amine dispersant where the polyester chain is derived from two or more different linear hydroxycarboxylic acids or lactones thereof and a residue of an ethylenically unsaturated group; and WO 98/19784 discloses a dispersant of the formula T-(A)n-(B)p—Z where A and B are each independently oxyalkylene carbonyl groups derivable from various lactones and Z is an acidic or basic group such as polyethyleneimine or phosphate. While such dispersants may be tailored for use in polar or non-polar liquid media, it has now been found that a further improved performance in polar liquid media may be obtained by replacing the polyester chain with a polyester/polyamide chain.